1. Field of the Invention
This invention relates to the field of fasteners. More particularly, this invention relates to the field of a tamper-resistant nut for bicycle axles.
2. Description of Related Art
To keep an object fixed and locked in place, threaded fasteners such as nuts and bolts are commonly used. Common tools, such as a wrench or variations on a wrench, are used to install and remove fasteners. Understandably, as simple as it is to secure an object with a fastener, it is just as simple to remove the fastener with a common tool. Therefore, anyone from the owner of the property to a thief who has access to these basic tools will be able to disassemble the object effortlessly. Essentially, this opens the door for unwanted removal and theft. As a result of this problem, tamper-resistant fasteners have been suggested offering elements of security against unwanted tampering. Some fasteners are shaped spherically making it difficult to grasp onto them using common tools. Others include a smooth outer surface to the product in order to reduce leverage, preventing unloosening. Also, some provide a special key so that only the owner will be able to tighten and loosen the fastener.
U.S. Pat. No. 5,097,686 entitled “Security Locking System for Vehicle Wheel Nuts” describes a cover cylinder that covers a vehicle's lug nuts and has a locking mechanism over it. Although this prevents unwanted tampering and unfastening of the nut, it requires two parts: the original nut as well as the cover cylinder as opposed to one nut with a special unfastening configuration.
U.S. Pat. No. 5,199,838 entitled “Nut for Use on Roadways, Runways, in Reinforced Concrete Construction, and the Like” describes a primarily spherical nut for use on roadway apparatuses. The spherical shape of the nut makes removal with the most common tools difficult. The nut, however, is still vulnerable to being opened with certain tools such as a spanner wrench.
U.S. Pat. No. 4,674,306 entitled “Vehicle and Assembly Locking and Wrenching Apparatus” describes a specific device for a vehicle lock, where that device is used in conjunction with a tamper-proof fastener. The apparatus provided is tailored to the unique lock. The nut has an “incised front face and arcuate sides parallel to the face, surrounded by cylindrical, annual rings that prevent the gripping and turning of the nuts.” However, a universal socket wrench will be able to compromise this device.
U.S. Pat. No. 5,033,501 entitled “Fire Hydrant Cap and Actuating Tool Therefor” describes a dome shaped fire hydrant cap that provides enhanced security against removal. The cap has cutouts on the front of the dome surface to work with a special tool for fastening/removal. However, similar to EP patent 1203164, the cap is still vulnerable to unwanted tampering/removal by using a universal socket wrench as the cutouts are not hidden and are on the face of the cap.
U.S. Pat. No. 4,302,137 entitled “Anti-Tamper Fastening Means” describes a nut with a curved surface and circular openings for pins to grab and rotate the nut. This nut is covered by a sleeve to further prevent tampering. However, this adds a second component to be used with the nut and thus makes it more difficult, complicated, and slower to unfasten the nut.
U.S. Pat. No. 4,125,051 entitled “Tamperproof Fastener” describes a fastener in which the “upper surface of the head is configured to include a very short cylindrical boss, coaxial of the fastener and a plurality of ribs extending radially outward.” This device uses a low profile headed design. It protects against high-profile tools; therefore, it is still susceptible to unwanted removal, just with “harder-to-find” tools.
U.S. Pat. No. 4,018,111 entitled “Tamper Resistant Fastener and Tool for Operating Same” describes a fastener with a head having a flat top surface and a smooth circular sidewall. The head has an offset opening to be filled with a complementary pin on a special key. This type of fastener is tamper resistant and prevents theft as when it is secured, it works in conjunction with a circular washer having a smooth frustoconical sidewall that covers the head.
U.S. Pat. No. 3,818,731 entitled “Nut Lock” describes a lock for preventing unauthorized removal of a nut. In a single casing, a plate having a flange at one edge is locked in a housing. The nut is threaded on a stud and the housing locked in place to prevent access to the nut. In a separate embodiment, such as where a cable having a coupling member is to be protected, the plate has an aperture shaped to receive the coupling member.
U.S. Pat. No. 7,673,482 entitled “Wheel Lock” describes an anti-theft device for preventing removal of a wheel from an axle. The wheel lock includes a cup shaped base piece with an opening to receive a wheel stud for threaded interaction with a lug nut, which will clamp the base portion to the wheel. A cup shape encloses the stud and lug nut. The cover piece interlocks with the locking portion to prevent tampering and rotation of the cover piece. The cover piece may include a flange that bears against the rim of the base portion giving the wheel lock an exterior surface that is hard to pry apart.
U.S. Pat. No. 4,645,397 entitled “Tire Theft Prevention Device” describes a device that purports to prevent theft of items having threaded nuts or the like, particularly truck tires. It includes a tamper-proof fastener having a locking cap which engages the underlying lug bolt and a seal which surrounds the locking cap and the lug nut of the tire to be secured. The seal moves freely about the locking cap and the lug nut, preventing anyone from loosening the lug nut without first breaking the seal. This invention is based on covering the lug nut thereby preventing access to the threaded nuts.
U.S. Pat. No. 4,880,344 entitled “Device for Preventing Loosening of a Member” describes a device for preventing tampering or loosening of a prismatic member such as a nut, screw head or bolt, or particularly a lock nut of a wheel of an automobile vehicle. The cap includes a transverse bottom and a cylindrical skirt in one piece with the bottom and a mechanism means for locking the prismatic member received in the cap in order to prevent the loosening of the respective member.
U.S. Pat. No. 4,825,669 entitled “Wheel Lug Nut Cover” describes a lug nut cover on a vehicle wheel secured to a vehicle. A mounting bracket and a lug nut cover both have elongated holes which makes them universal and allows them to fit a substantial number of lug bolt spacings. The cover is fitted onto special lug nuts as an extension. This mounting bracket works with the locking mechanism to hold the lug nut cover firmly in place.
U.S. Pat. No. 6,341,927 entitled “Tamper Resistant Fastener” describes a tamper resistant device that has a head with two or more tear-shaped cutouts having discontinuous sidewalls. A key having downwardly projecting pins mate into corresponding slots in the device. The specification claims that these tear-shaped cutouts prevent a tool other than the specific key provided from engaging the device and thus rotating it in a counter clockwise direction. However, other tools such as a gator grip socket wrench are able to gain leverage on the cutouts and rotate the fastener count-clockwise. The shape of the cutouts and the slope in the cutouts open the door to other tools compromising the device as well.
U.S. Pat. No. 5,863,166 entitled “Anti-Theft Locking Device” describes a device for attaching bicycle components to the bicycle frame. The device includes a threaded bolt with a matching nut. The nut has a rotatable casing around the outer surface. The key engages with the nut giving the user access. The key and the nut share at least one spigot and at least one hole in order to engage with each other.